Objective: To study rates of incomplete excision of basal (BCC) and squamous (SCC) cell cancer by Australian general practitioners with a special interest. Design: Records review. Setting: A network of 15 primary care skin cancer clinics across Australia. Participants: Fifty-seven physicians performing excisions of 9417 BCCs and SCCs in a single network of 15 primary care skin cancer clinics across Australia between 2005 and 2007. Main Outcome Measures: Rates of incomplete excision according to physician, clinic, anatomic location of the lesion, and whether a previous biopsy had been performed. Results: Four hundred forty-three of 6881 BCCs (6.4%) and 159 of 2536 SCCs (6.3%) were excised incompletely. Incomplete BCC and SCC excisions were more frequent on the head and neck (282 of 2872 excisions [9.8%] and 97 of 861 [11.3%], respectively) than elsewhere. Ears (74 of 388 excisions [19.1%]) and nose (78 of 546 [14.3%]) had the highest rates of incompletely excised BCCs, and ears (26 of 144 excisions [18.1%]) and forehead (20 of 157 [12.7%]) had the highest rates of incompletely excised SCCs. Of all BCC excisions, 67.3% were once-off excisions with no previous biopsy, and these excisions were more likely to be incomplete (odds ratio, 1.73; 95% confidence interval, 1.36-2.20) than those with a previous biopsy. There was, however, substantial variation in frequency of incomplete excision between clinics for BCC (ranging from 3.3% to 24.7%) and SCC (ranging from 0% to 17.2%) and between physicians within clinics(BCC ranging from 0% to 31.1%, and SCC ranging from 0% to 23.5%). Conclusions: Overall frequency of incomplete excision is low and similar to that in other reports. However, high frequency in high-risk sites, low rates of previous biopsy, and substantial variation in performance between physicians and clinics suggests there is significant opportunity to further improve health outcomes.