As relevant literature is scarce, this study was undertaken to assess the donor site morbidity of cross-finger flaps. It included 23 patients who had undergone reconstruction of a finger defect with a cross-finger flap. Any additional trauma to the donor finger was an exclusion criterion. Split thickness skin grafts were employed for donor site closure in 13 cases, full thickness skin grafts were used in 10 cases. Follow-up time averaged 83 months. Active and passive total range of motion of the donor finger and maximal pinch grip strength in kilopascals were measured. Both parameters were compared to the corresponding finger of the other hand. The donor site scar was evaluated for instability and pain in the donor finger was determined subjectively with a visual analogue scale. Cold intolerance and the cosmetic appearance of the donor site were also assessed. Active total range of motion of the donor fingers averaged 156 degrees . Average active total range of motion of the contralateral control fingers was 173.6 degrees . There was a significant difference between the donor fingers and the control fingers (p = 0.03) but not between split thickness and full thickness grafted donor sites (p = 0.91). Grip strength was significantly impaired in the donor fingers (p = 0.03), but there was no significant difference between split thickness and full thickness grafted donor sites. Subjective cosmetic evaluation by the patients revealed significantly better results for full thickness grafted donor sites. Donor finger pain averaged 2.4 with a range of 0-8. Five of the 13 patients with split thickness grafted donor sites and two of the 10 patients with full thickness grafted donor sites mentioned cold intolerance. In conclusion, the cross-finger flap is a secure and valuable option. There is, however, significant donor site morbidity. Our results suggest that alternative solutions should also be considered and if a cross-finger flap is employed, donor sites should be closed with full thickness grafts.