Ageing is associated with anabolic resistance; a reduced sensitivity of myofibrillar protein synthesis (MPS) to postprandial hyperaminoacidemia, particularly with low protein doses. Impairments in postprandial skeletal muscle blood flow and/or microvascular perfusion with hyperaminoacidemia and hyperinsulinemia may contribute to anabolic resistance. We examined whether providing citrulline, a precursor for arginine and nitric oxide synthesis, would increase arterial blood flow, skeletal muscle microvascular perfusion, MPS, and signalling through mTORC1. Twenty one elderly males (65-80 y) completed acute unilateral resistance exercise prior to being assigned to ingest a: high dose (45g) of whey protein (WHEY), or a low dose (15g) of whey protein with 10g of citrulline (WHEY+CIT), or with 10g of non-essential amino acids (WHEY+NEAA). A primed continuous infusion of L-[ring-¹³C₆] phenylalanine with serial muscle biopsies was used to measure MPS and protein phosphorylation, while ultrasound was used to measure microvascular circulation under basal and postprandial conditions in both a rested (FED) and exercised (EX-FED) leg. Argininemia was greater in WHEY+CIT vs. WHEY and WHEY+NEAA from 30-300 min post-exercise (P<0.001), but there were no treatment differences in blood flow, or microvascular perfusion (all P>0.05). Phosphorylation of p70S6k^Thr389 was greater in WHEY vs. WHEY+NEAA (P=0.02). Postprandial MPS was greater in WHEY vs. WHEY+CIT and WHEY+NEAA under both FED (WHEY: ~128%; WHEY+CIT: ~56%; WHEY+NEAA: ~38%) and EX-FED (WHEY: ~251%; WHEY+CIT: ~124%; WHEY+NEAA: ~108%) conditions (P=0.003). Citrulline co-ingestion with a low quantity of protein was ineffective in augmenting the anabolic properties of protein compared to non-essential amino acids.