INTRODUCTION: To assess the quality of transurethral resection of bladder tumors (TURBTs) performed by "senior" and `junior` urologists for pT1 tumors in terms of detrusor muscle (DM) presence and recurrence rate at 3 month first cystoscopy (RR-FC). Non-muscle invasive bladder cancer (NMIBC) is a heterogeneous group with differing biological potentials. Tumors invading lamina propria (pT1) have an increased propensity for recurrence and progression. Accurate staging at the time of primary TURBT, including the presence of DM, is crucial to avoid understaging and unnecessary delay in definitive treatment. MATERIALS AND METHODS: We analyzed our maintained bladder tumor database (TURBTs from 2002 to 2009) and selected patients diagnosed with pT1 bladder tumors. Data on surgeon status, tumor characteristics (size, TNM stage 2009, grade, DM presence) and RR-FC were retrieved. Surgeons were stratified into `senior` and `junior` according to the years of prior training. Results: Of the 340 TURBTs for pT1 tumors, `senior` and `junior` surgeons performed 237 (69.7%) and 103 (30.3%), respectively. Overall, 238 (70%) TURBTs had DM in the specimen, including 175 (73.8%) and 63 (61.3%) for the `senior` and `junior` operators, respectively (p = 0.02). The overall RR-FC was 37.4% (n = 127) and was significantly different for DM presence and DM absence (30.7% versus 52.9%; p = 0.01). On multivariate analysis, tumor recurrence was associated with `junior` operator experience independent of the presence or absence of DM (OR = 2.33 [1.45-3.74]) p = 0.01). CONCLUSIONS: The presence of DM in a primary TURBT for pT1 NMIBC is directly associated with operator experience, with an associated increased 3 month recurrence rate for `junior` resectionists.