The 1.5 μm fluorescence shape and lifetime of Er3 + -activated tellurite glasses have been investigated. The measures on bulk system have been compared with those obtained on powders, showing that the self-absorption effect broadens the emission spectrum and lengthens the lifetime. It has been demonstrated that the bandwidth and lifetime measurements depend on the absorption coefficient α(λ) and on the distance d between the focused exciting laser beam and the exit face of a bulk glass sample. The actual emission spectrum has been reconstructed from the α(λ)·d knowledge. Lifetime lengthening cannot be determined from α(λ)·d and, to obtain actual lifetime for highly Er3 + -doped glasses, measurements on powders are required.