Background: We reviewed the incidence of and risk factors for venous thromboembolic complications in our population of kidney (KTx) and simultaneous kidney-pancreas transplant (SPK) recipients. methods: Information was collected retrospectively from a database on 1833 KTx and 276 SPK recipients who underwent transplant surgery between January 1985 and August 1995. Results. The incidence of deep venous thrombosis (DVT) was 6.2%(n = 132), with significantly higher rates after SPK (18.1%) vs. KTx (4.5%) (P<0.001). The number of DVT episodes was highest in the first month; 17.5% occurred during this tine. For KTx recipients, early thrombotic events were more common on the side of the graft (P=0.03); however, after 1 month, no correlation existed between the side of the graft and the side of DVT. For SPK recipients, DVT tended to be more common on the side of the pancreas (57%) vs. the kidney (43%) (P=0.10). By multivariate analysis, risk factors for DVT were: age >40 years (odds ratio [OR]=2.2, P<0.001), diabetes mellitus (DM) (OR=2.0, P=0.002) previous DVT (OR=4.4, P=0.001) and SPK transplant (OR=2.8, P<0.001). Pulmonary embolus (PE) was identified in 44 recipients (incidence, 2.1%) and was fatal in 13 (30%). The incidence was significantly higher in SPK (4.71%) vs. KTx recipients (1.69%) (P<0.01). The risk of death from PE was 0.5% in KTx recipients and 1.37% in SPK recipients (P=0.08). Risk factors for PE included DM (OR=2.6, P=0.005) and recent DVT (OR=8.9, P=0.0001). Conclusions. Based on risk and extrapolating from the general surgical literature, our recommendations for prophylaxis against DVT are use of graduated compression stockings for all recipients and, in addition, low- dose heparin for moderate and high-risk recipients (previous DVT, SPK, age>40 years, DM).