  Evidence for a narrow baryon state at 1528 +- 2.6(stat) +- 2.1(syst) MeV is
presented in quasi-real photoproduction on a deuterium target through the decay
channel p,K0 to p,pi+,pi-. The statistical significance of the peak in the p,K0
invariant mass spectrum is 4 standard deviations and its extracted intrinsic
width Gamma = 17 +- 9(stat) +- 3(syst) MeV. This state may be interpreted as
the predicted S=+1 exotic Theta+ (uudd\bar{s}) pentaquark baryon.
