  We prove the following results. If $X_3$ is a generic complete intersection
Calabi-Yau 3-fold, (1) then for each natural number $d$ there exists a rational
map \par\hspace{1 cc} $c\in Hom_{bir}(\mathbf P^1, X_3)$ of $deg(c(\mathbf
P^1))=d$, (2) further more all such $c$ are immersions satisfying
\begin{equation} N_{c(\mathbf P^1)/ X_3}\simeq \mathcal O_{\mathbf
P^1}(-1)\oplus \mathcal O_{\mathbf P^1}(-1).
