| | | | | | | | | | |  | Major Transactions |
| | | | Thursday, October 13th, 1966 | | SS J. Kennedy was designated for assignment and placed on waivers. | | Placed 2B D. Menke on the active roster. |
| Thursday, October 6th, 1966 | | 2B D. Menke was designated for assignment and placed on waivers. | | Purchased the contract of SS C. Peterson from Triple A Toronto. |
| Friday, August 26th, 1966 | | Signed SP P. Ramos to a 2-year contract extension worth a total of $95,200. |
| Friday, August 19th, 1966 | | Signed LF W. Horton to a 2-year contract extension worth a total of $135,600. | | Signed MR D. Radatz to a 2-year contract extension worth a total of $126,400. |
| Thursday, June 2nd, 1966 | | Signed free agent MR J. Constable to a 1-year contract worth a total of $99,000. | | Signed free agent MR J. Lehew to a 1-year contract worth a total of $43,200. | | Demoted MR D. Eilers to Triple A Toronto. | | Placed MR J. Constable on the active roster. |
| Friday, May 27th, 1966 | | Placed MR C. Pascual on the 60-day disabled list. | | Purchased the contract of MR D. Eilers from Triple A Toronto. |
| Wednesday, May 11th, 1966 | | Signed SP B. Shaw to a 3-year contract extension worth a total of $220,800. |
| Saturday, May 7th, 1966 | | Signed C J. Gonder to a 3-year contract extension worth a total of $152,400. |
| Sunday, March 27th, 1966 | | Signed SP B. Hendley to a 2-year contract extension worth a total of $1,726,400. |
| Saturday, March 26th, 1966 | | Signed CF H. Aaron to a 3-year contract extension worth a total of $4,046,200. | | Signed SP B. Bolin to a 2-year contract extension worth a total of $2,082,000. |
| Monday, March 14th, 1966 | | Signed free agent MR B. Daley to a 1-year contract worth a total of $82,400. | | Signed free agent CF D. Snider to a 1-year contract worth a total of $41,400. | | Placed CF D. Snider on the active roster. | | Placed MR B. Daley on the active roster. |
| Monday, February 21st, 1966 | | Signed free agent RF B. Skinner to a 1-year contract worth a total of $355,000. |
| Sunday, February 20th, 1966 | | Placed MR J. Constable on the active roster. | | Activated MR J. Constable from the 60-day disabled list. |
| Monday, January 10th, 1966 | | Signed free agent SP B. Shaw to a 1-year contract worth a total of $47,600. |
| Monday, December 13th, 1965 | | Placed 2B D. Menke on the active roster. | | Activated 2B D. Menke from the 60-day disabled list. |
| Wednesday, December 1st, 1965 | | Drafted C J. Gonder in the 1965 rule 5 draft (Pick 20, Round 1, 20th overall Pick). |
| Tuesday, November 16th, 1965 | | SS L. Aparicio becomes a free-agent. | | 2B C. Peterson received a 1-year contract through automatic renewal worth a total of $24,774. | | MR B. Heffner received a 1-year contract through automatic renewal worth a total of $24,774. | | RF B. Skinner becomes a free-agent. | | MR A. Gatewood received a 1-year contract through automatic renewal worth a total of $24,774. | | MR K. Sanders received a 1-year contract through automatic renewal worth a total of $24,774. | | SP J. Lonborg received a 1-year contract through automatic renewal worth a total of $24,774. | | MR D. Eilers received a 1-year contract through automatic renewal worth a total of $24,774. | | C B. Uecker received a 1-year contract through automatic renewal worth a total of $24,774. | | RF R. Reichardt received a 1-year contract through automatic renewal worth a total of $24,774. |
| Saturday, November 13th, 1965 | | 2B D. Menke received a 1-year contract through arbitration worth a total of $201,670. | | SP B. Hendley received a 1-year contract through arbitration worth a total of $383,400. | | SP B. Bolin received a 1-year contract through arbitration worth a total of $463,440. | | MR J. Constable received a 1-year contract through arbitration worth a total of $54,432. | | 1B R. Staub received a 1-year contract through arbitration worth a total of $348,300. | | LF W. Horton received a 1-year contract through arbitration worth a total of $26,634. | | LF S. Johnson received a 1-year contract through arbitration worth a total of $26,910. |
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